Aside from claiming the title of the largest animal known to have ever lived, the blue whale (Balaenoptera musculus) possesses a heart big enough to house a human. The heart of an average sized blue whale weighs 180 kg (400 lb) and is also the largest known in any animal.

During the first seven months of its life, a blue whale calf drinks approximately 380 litres (100 US gal) of milk every day. Blue whale calves gain weight quickly, as much as 90 kilograms (200 lb) every 24 hours. Even at birth, they weigh up to 2,700 kilograms (6,000 lb) - the same as a fully grown hippopotamus.

Blue whales have proportionally small brains, only about 6.92 kilograms (15.26 lb), about 0.007% of its body weight, although with a highly convoluted cerebral cor ...